Universal Mobile Telecommunications System (UMTS) is a ‘third generation’ (3G) mobile communications system developed within a framework known as IMT-2000 (International Mobile Telecommunications-2000). UMTS will play a key role in creating the mass market for high-quality wireless multimedia communications. UMTS will enable many wireless capabilities, delivering high-value broadband information, commerce and entertainment services to mobile users via fixed, wireless and satellite networks. UMTS will speed convergence between telecommunications, information technology, media and content industries to deliver new services and create revenue-generating services. Compared to its 2G or 2.5G wireless cellular counterparts, UMTS will deliver low-cost, high-capacity mobile communications with data rates on the order of 2 Mbit/sec under stationary conditions with global roaming and other advanced capabilities.
One drawback of the UMTS network is the high cost of spectrum and low data rates as compared to WLANs (Wireless Local Area Networks). The overall cost of a cellular infrastructure is very high compared to the cost of a WLAN infrastructure both in terms of cost of the spectrum, which in the case of WLAN is free, and the overall system cost for the supported bandwidth. On the other hand, it is more difficult for a WLAN to have the wide area coverage offered by a cellular system. In order to have the advantages from both cellular and WLAN technologies, the WLAN may be an extension of the cellular network in hotspot areas.
Since Universal Mobile Telecommunications System (UMTS) networks use expensive bandwidth and end up delivering low data rates, it would be advantageous to utilize wireless local area networks (WLANs) in hotspots for high data rates and to utilize UMTS for ubiquitous coverage. To accomplish this, the mobile terminal will need to transition quickly and easily from one network to another.